For many large-scale rubber products including conveyor belts, rubber crawlers, and large-scale gaskets made of rubber, a procedure of disposing an unvulcanized rubber for adhesion (also referred to as “tie rubber”) at an adhesion interface upon adhesion (bonding) of vulcanized rubber components to be adhered or a vulcanized rubber component to an unvulcanized rubber component has been conventionally used.
For example, in Japanese Unexamined Patent Application Publication No. 2008-248003A, the applicant of the present technology has proposed “a method of adhering together adherend rubbers including a rubber composition containing a diene-based rubber and a sulfur-containing organic compound, using an unvulcanized rubber for adhesion including a rubber composition containing a diene-based rubber and a sulfur-containing organic compound at the adhesive interface between the adherend rubbers, wherein a total sulfur amount X of the adherend rubber is from 0.16 to 0.54 parts by mass relative to 100 parts by mass of the diene-based rubber in the adherend rubber, a total sulfur amount Y of the rubber for adhesion is from 0.20 to 1.00 parts by mass relative to 100 parts by mass of the diene-based rubber in the rubber for adhesion, and a ratio (Y/X) of the total sulfur amount Y to the total sulfur amount X is from 1.25 to 2.50”.
However, in the method of adhering described in Japanese Unexamined Patent Application Publication No. 2008-248003A, a vulcanization (crosslinking) system using an organic peroxide such as dicumyl peroxide is not considered since an object thereof is to “provide an adhesion method that is capable of favorably adhering together rubber products that each contain a sulfur-containing organic compound such as morpholine disulfide and have excellent heat resistance.” For example, this shows that the adhesion method cannot be applied to adhesion of a heat-resistant conveyor belt including a cover rubber containing of a rubber composition containing an ethylene-α-olefin copolymer and the like.